LAN9500 Datasheet, PDF (113/213 Pages) SMSC Corporation – USB 2.0 to 10/100 Ethernet Controller Promiscuous mode

LAN950x
The Host Processor is connected to a Chipset containing the Host USB Controller (HC). The USB Host Controller inter-
faces to the device via the DP/DM USB signals. An Embedded Controller (EC) signals the Chipset and the Host pro-
cessor to power up via an Enable signal. The EC interfaces to the device via four signals. The PME signal is an input
to the EC from the device that indicates the occurrence of a wakeup event. The VBUS_DET output of the EC is used
to indicate bus power availability. The PME_CLEAR (nRESET) signal is used to clear the PME. The PME_MODE_SEL
signal is sampled by the device when PME_CLEAR (nRESET) is asserted and is used by the device to determine
whether it should remain in PME mode or resume normal operation.
GPIO pins are used for PME handling. The pins used depend on the value of the PHY_SEL pin, which determines PHY
mode of operation. In Internal PHY mode of operation, GPIO0 is reserved for use as an output to signal the PME. GPIO1
is reserved for use as the PME_MODE_SEL input. GPIO8 and GPIO9 are reserved for analogous use, respectively, in
External PHY mode of operation.
The application scenario in Figure 6-1 assumes that the Host Processor and the Chipset are powered off, the EC is
operational, and the device is in PME mode, waiting for a wake event to occur. A wake event will result in the device
signaling a PME event to the EC, which will then wake up the Host Processor and Chipset via the Enable signal. The
EC asserts VBUS_DET after the USB bus is powered, sets PME_MODE_SEL to determine whether the device is to
begin normal operation or continue in PME mode, and asserts PME_CLEAR (nRESET) to clear the PME.
The following wake events are supported:
• Wakeup Pin(s)
The GPIO pins not reserved for PME handling have the capability to wake up the device when operating in PME
mode. In order for a GPIO to generate a wake event, it must be configured as an input. GPIOs used as wake
events must also be enabled by the GPIO_WAKE register, see Section 7.3.20, "General Purpose IO Wake Enable
and Polarity Register (GPIO_WAKE)". On POR or nRESET, all GPIOs default to inputs and the default value of
the GPIO Wake 0-10 (GPIOWKn) field of the GPIO_WAKE register is set from the contents of the EEPROM.
During PME mode of operation, the GPIOs used for signaling (GPIOs 0 and 1 or GPIOs 8 and 9) are not affected
by the register defaults.
GPIO10 is available as a wakeup pin in External PHY mode, while GPIOs 2 - 10 are available in Internal PHY
Mode. The GPIO10 Detection Select bit in the GPIO PME Flags byte of the EEPROM sets the detection mode for
GPIO10 in both External and Internal PHY mode (if enabled via the GPIO_WAKE register), while GPIOs 2 - 9 are
active low (by default) when operating in Internal PHY mode.
• Magic Packet
Reception of a Magic Packet when in PME mode will result in a PME being asserted.
• PHY Link Up
Detection of a PHY link partner when in PME mode will result in a PME being asserted.
In order to facilitate PME mode of operation, the GPIO PME Enable bit in the GPIO PME Flags field, must be set and
all remaining GPIO PME Flags field bits must be appropriately configured for pulse or level signaling, buffer type, and
GPIO PME WOL selection. The PME event is signaled on GPIO0 (External PHY mode) or GPIO8, depending on the
PHY Mode of operation.
The PME_MODE_SEL pin (GPIO1 in Internal Mode of operation, GPIO9 in External Mode of operation) must be driven
to the value that determines whether or not the device remains in PME mode of operation (1) or resumes normal oper-
ation (0) when the PME is recognized and cleared by the EC via PME_CLEAR (nRESET) assertion.
Note 1: The device’s software driver is unaware of PME mode. No internal mechanism exists for the driver to exam-
ine the internal hardware to determine the setting of the GPIO PME Flags read from the EEPROM on POR
or nRESET. PME mode is not visible via the GPIO registers or via the INT_STS register. I.e., if a GPIO pin
or reception of a Magic Packet results in a PME, the INT_STS register is not updated to indicate the occur-
rence of the event. The driver has no mechanism available to clear the PME. The driver can not program
any GPIO register associated with the PME until the EC asserts nRESET to clear PME mode.
2: When in PME mode, nRESET or POR will always cause the contents of the EEPROM to be reloaded.
3: GPIO10 may be used in PME and External PHY mode to connect to an external PHY’s Link LED, in order
to generate a PHY Link Up wake event.
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DS00001875A-page 113